Field of the Invention
The invention relates to a microwave module for a fill level measuring device operating with the runtime method, having at least one chip for generating and/or receiving microwave signals and having at least one carrier element.
Description of Related Art
In one possibility for measuring the fill level of a medium in a container, microwave signals are emitted in the direction of the surface and the signals reflected there are received. The distance between the measuring device and the surface of the medium can be determined and, from this, the fill level can be determined using known variables of the measuring system. Thus, the measuring method is called runtime or radar method. Furthermore, microwave signals can be generated and emitted continuously or in pulses.
Corresponding measuring devices usually have an electronics unit that generates or processes the microwave signals, and an antenna element that, for example, emits the microwave signals into space or guides them along a conductor path structure—e.g. a wire or rod. The term time domain reflectometry TDR is used in conjunction with the coupling in and out of the signals from a waveguide—also called probe.
In many implementations, a microwave module having a chip, which is used for generating and evaluating or processing signals, is located in the electronics unit.
Thus, U.S. Pat. No. 8,269,666 B2 describes, for example, a microwave module with a chip located on a HF printed circuit board. A metallization is located under the printed circuit board in one implementation. A housing is provided on the side of the printed circuit board, on which the chip is located. A similar construction is also shown in U.S. Pat. No. 7,355,547 B2.
The use of a copper carrier as a heat sink below the chip is given in conjunction with similar microwave modules, for example, in the dissertation “MCM Integration Technologies for 60-80 GHz Applications” by Janusz Grzyb, ETH Zurich, 2004.
A chip and a carrier element carrying this chip can be gathered, for example, from the dissertation “Methoden and Techniken zur Integration von 122 GHz Antennen in miniaturisierte Radarsensoren” by Stefan Beer, Karlsruhe, 2013. Bond wires are disclosed there for connecting the chip to the upper side of the carrier element.
Waveguides, for example, are recommended for emitting microwave signals.
An arrangement with a chip, which is connected to a waveguide via a ring coupler also rat race coupler, for example, is disclosed in the article “SIGE-SCHALTUNGEN—RADAR DER ZUKUNFT?” by Prof. Dr.-Ing. Nils Pohl, Annual Report 2012, Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR, pages 15-17.
An arrangement with a rod antenna is shown, for example, in European Patent Application EP 2 219 045 B1.
One implementation of an antenna element consisting of an opening in a substrate as well as a cap is shown in German Patent Application DE 102 43 671 B3 and corresponding U.S. Pat. No. 7,336,141 B2.
German Patent Application DE 601 31 643 T2 describes different carrier elements for microwave chips.
German Patent Application DE 10 2011 015 894 A1 and corresponding U.S. Pat. No. 8,981,867 B2 show, for example, the coupling in of signals in the antenna element.